Colorectal cancer that develops in the large intestine (cecum, colon, rectum) is ranked third in males and first in females as a high-mortality cancer in Japan in 2014.
The cause of colorectal cancer remains to be determined. However, it has been pointed out that so-called Western-style dietary habit, including mainly eating meat, are associated with the development of colorectal cancer, as well as the intestinal environment, particularly an abnormal intestinal flora is associated with colorectal cancer (see, for example, Non-Patent Literatures 1 and 2). Some Lactobacillus or Bifidobacterium species, which are classified as good bacteria (probiotics), have also been reported to produce substances with an antitumor activity (see, for example, Non-Patent Literatures 3 and 4).
It has long been proposed and demonstrated that the intake of probiotics contributes to health maintenance or improvement with few adverse events. Therefore, it is expected that the discovery and use of useful ingredients having an antitumor activity derived from probiotics will lead to the provision of safe antitumor agents with fewer side effects and therapies for cancer using the same.